This is what i came up with. It is meant to be worn as a halo style headband but I'm not sure about the measurements. I used about 19" of elastic. From what I can tell this is a little bit bigger than what most use (from what little info I can find) but I want the twisting to still look in tact and I don't want it to be too tight on her forehead. The customer's dd is about 4 yrs old.

Does that sound like it will work? It fits my 3 yr old o.k. but the next age I have is 10 so I don't have a whole lot to work with as far as sizing. Does anyone have a sizing guide they use for this type of headband?

Also, what do you think about the headband itself...do you think it goes with the outfit o.k.?